Movie studios have a problem in that they have not established a successful mechanism to provide a chain of custody for their video or other media. In other words, their video is not linked to a current person, usually an employee, whom is in possession of the video. This problem is described even more fully in a paper by Simon Byers, et al. titled “Analysis of Security Vulnerabilities in the Movie Production and Distribution Process,” Sep. 13, 2003, (http://lorrie.cranor.org/pubs/drm03-tr.pdf), incorporated herein by reference.
Digital watermarks can be used to link video to a specific person. I disclose herein several processes to make this linking efficient in terms of a conventional video workflow.
Digital watermarking is a process for modifying physical or electronic media to embed a hidden machine-readable code into the media. The media may be modified such that the embedded code is imperceptible or nearly imperceptible to the user, yet may be detected through an automated detection process. Most commonly, digital watermarking is applied to media signals such as images, audio signals, and video signals. However, it may also be applied to other types of media objects, including documents (e.g., through line, word or character shifting), software, multi-dimensional graphics models, and surface textures of objects.
Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host media signal, and a decoder that detects and reads the embedded watermark from a signal suspected of containing a watermark (a suspect signal). The encoder embeds a watermark by subtly altering the host media signal. The reading component analyzes a suspect signal to detect whether a watermark is present. In applications where the watermark encodes information, the reader extracts this information from the detected watermark.
Several particular watermarking techniques have been developed. The reader is presumed to be familiar with the literature in this field. Particular techniques for embedding and detecting imperceptible watermarks in media signals are detailed in the assignee's U.S. Pat. Nos. 6,122,403 and 6,614,914, which are hereby incorporated by reference.
One aspect of the invention provides workflow efficiency by matching a time based log of personal computer (PC) users with a watermark embedder ID (e.g., a number or plural-bit identifier) and date/time stamp. The embedder ID is uniquely associated with the PC, so that a user can be matched to a computer via the embedder ID and a log of user activity on the PC. This system works automatically, without an operator needing to keep track of IDs and video that is processed on the system.
Another aspect of the invention is a system responsive to a rights command. The rights command requires a video player to embed a forensic ID in content, where a watermark embedder—and not the rights command—controls which data is embedded. More specifically, a rights language, such as MPEG-21 REL (ISO/EEC 21000-5 draft, incorporated herein by reference) is used to mandate watermark embedding, but is not used to specify a particular identifier or data to be embedded.
Still another aspect is an encrypted video file with certain video segments duplicated therein. The duplicated segments can be encrypted according to different keys. The segments are used to generate different unique watermarks when the content is rendered by applying device specific decryption keys. Consider a typical movie trail. A movie is passed from one executive to another, perhaps even to editors and directors, each giving their approval prior to release of the movie. The video is played on a rendering device (e.g., video player). To establish an audit trail the player preferably generates a unique ID that is associated with the player or executive in the video, based upon selective decryption of the duplicated video segments as dictated by device-specific keys. An embedded identifier is then dependent upon which player is rendering the video (e.g., which movie studio executive is currently viewing the video as the video is passed along to each other after approval of a master version for release). The embedding happens during viewing (a.k.a. rendering) in the player.
(Related information for embedding is found, e.g., in EP 1134977 entitled “Method and system for providing copies of scrambled content with unique watermarks, and system for descrambling scrambled content” (incorporated herein by reference) and J. Benaloh, et al's, “Efficient Fingerprinting to Protect Digital Content,” a copy of which is found at http://research.microsoft.com/crypto/FingerMark.ppt, which is incorporated herein by reference.)
Yet another aspect of the present invention is identifying an intended recipient of a DVD disk by embedding a recipient identifier in a DVD disk master file during transport of the disk to the recipient.
The foregoing and other features, aspects and advantages of the present invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.